Reaming bit



March 27, 1956 G. DIMITRIEFF REAMING BIT Original Filed Nov. 10, 1951 Fl. 1 V

FIG. 2

United States Patent O REAMIN G BIT George Dimt'riei, Noranda, Quebec, Canada Original application November 10, 1951, Serial No. 255,765. Divided and this application May 25, 1953, Serial No. 357,079

Claims priority, application Canada December 6, 1950 1 Claim. (Cl. 25E-73) This application relates to reaming bits, as employed for reaming out or enlarging holes which have been drilled by percussive rock drills, and is a division of copending application, Serial No. 255,765, filed November 10, 1951.

The bit commonly used for reaming out such holes is simply an enlarged bit similar to the bit employed for drilling the original hole. These bits strike the rock with a chisel-like edge and chip particles of rock from the bott-om of the hole. In holes of large diameter, where there is an increased volume of rock to be chipped out, progress is very slow. Bits of this type do not strike the rock in such a manner that the particles are broken into the hole previously drilled.

It has been proposed to employ a drill bit having reaming cutting edges formed rearwardly of an axial cutting face whereby the hole is produced and reamed out in the one drilling operation. However, the power required for such an operation and the resultant strain on the drill renders such a bit unfeasible in practical operation.

It is an object of the present invention to provide a reaming bit which is of simple and inexpensive manufacture, which may be readily mounted on a standard drill rod, which is efcient and satisfactory in operation, and which has a long operating life.

The invention will be described with reference to the accompany drawings, in which,

Figure 1 is a side elevation, partly in section, `of a drill assembly in accordance with the invention, and

Figure 2 is a plan view of the assembly.

In the drawing, 1 is a standard drill rod member having the usual shoulder 2 and end section 3 of non-circular cross-section, such a-s hexagonal, as shown.

A bit 4, in accordance with the invention, comprises a simple sleevelike member having an axial opening 5 extending therethrough, such opening being of non-circular cross-section for non-rotative engagement With a drill rod section, as indicated at 3. Moreover, since the opening 5 is adapted to receive a standard drill rod section, it is of uniform cross-sectional size throughout its extent, the wall of the opening being thereby parallel to the longitudinal axis of the bit.

The exterior side wall 6 of the bit is of uniformly tapered contour from end to end of the bit, one end of the bit being thus of reduced diameter as compared with the other end. The end Wall 7 at the reduced end of the bit is flat and lies in a plane normal to the axis of the bit for engagement with the shoulder 2. The surface of wall 6 adjacent its juncture with wall 7 is of uninterrupted circular contour to provide for ease of manufacture and greater structural strength.

The end wall S at the other or larger end of the bit is dished to impart a conical shape thereto. The Wall 8 is in cross-sectional contour a straight line having only unidirectional extent and extends from the Walls of opening 2,739,791 Fatented Mar. 27, 1956 ICC 5 to a meeting edge 10 with the tapered surface of wall 6. Thus, the walls of opening 5, 6, 7 and 8 form in crosssection a simple quadrilateral, with the result that formation of the bit is simple and its structure is strong.

The meeting edge 10, because of the tapered nature of surfaces 6 and 8, is of sharpened form and thus conveniently forms the cutting edge of the bit. A plurality of equidistantly spaced grooves or notches 9 are formed in the wall 6 and edge 10 to provide passages for washing of chips or cuttings out of the hole. The notches 9 divide the cutting edge 10 into a plurality of spaced sections each, of course, of arcuate form and lying on the circumference of the same circle.

Means for removably retaining the bit on the rod comprises a screw-threaded end portion 11 on section 3 of the drill rod and complementary internally threaded bushing 12 adapted to be readily applied to or removed from portion 11.

Portion 11 extends considerably beyond the cutting end of bit 4, when the latter is applied to the drill rod with end surface 7 in substantial abutment with shoulder 2, to constitute a pilot for the drilling assembly. The inner end of bushing 12, at the limit of its screw-threaded movement on portion 11 is in slightly spaced relation to the cutting end of the bit whereby the latter has a slight reciprocal play on the rod.

The previously drilled hole is indicated at 13 and the reamed out hole at 14. The usual Water hole is shown at 15 in the drill rod.

It will be apparent that the bit described may be readily and inexpensively manufactured. Moreover, in use, the bit may be conveniently and quickly applied to or removed from the drill rod member. In operation, the cutting edges 10, being disposed substantially normal to the diameter of the hole, chip the rock into the preformed hole 13.

I claim:

A reaming bit comprising a sleevelike member having an uninterrupted interior Wall forming an axial opening of non-cirsular dimensionally uniform cross-section extending from end to end of -said member, a uniformly tapered exterior side wall having a frusto-conical surface of uninterrupted contour extending from end to end of the member, said member being thereby of gradually increasing diameter from end to end thereof, a plane end wall at the reduced end of the member extending perpendicularly to the axis of the member from said interior wall to said exterior side wall, the portion of said exterior side Wall adjacent said plane end wall being of uninterrupted circular contour, and a dished end Wall at the other end of the member extending unidirectionally from said interior wall to said exterior side wall in a direction inclined with respect to the axis of said member to form a cutting edge at its juncture with said exterior side Wall.

References Cited in the file of this patent UNITED STATES PATENTS 48,914 Dickey July 25, 1865 163,636 Cheadle May 25, 1875 802,197 Clarkson Oct. 17, 1905 1,577,875 Rutherford et al Mar. 23, 1926 2,099,677 Cunningham Nov. 23, 1937 2,107,547 Pyle Feb. 8, 1938 2,147,343 Hokanson Feb. 14, 1939 2,281,614 Ogran May 5, 1942 FOREIGN PATENTS 13,998 Great Britain 1914 

